Perhaps the more interesting question is "How was data originally pronounced?". According to the Online Etymology Dictionary, the term first appeared in 1946, and was used early on in 1956 in the Data Processing Industry. According to a data processing industrialist, the term has been pronounced "day-ta" in his field for as long as he can remember.
–
mareoraftSep 2 '14 at 6:03

This sounds right to me. There's nothing more formal about the dahta pronunciation though. It's a dialectical, even personal matter.
–
NoldorinJan 26 '11 at 23:49

1

I think the t in 2 and 3 should be a d!
–
reinierpostApr 19 '12 at 17:27

What's the android's name on Star Trek? Say it with me...Day-ta. I rest my case.
–
user23235Jul 7 '12 at 7:25

@Greg That may be how the crew of the Enterprise pronounces the name of their droid, but that's flimsy evidence to rest a case on. NOAD lists two pronunciations; moreover, Macmillan's American edition lists one, while their British edition lists a different one. M-W lists three ways to say the word, presumably all valid.
–
J.R.Jul 7 '12 at 17:21

3

@reinierpost What you are calling a ‘d’ is phonologically a simple flap, written as [ɾ] to represent that particular allophone of phonemic /t/. I don’t think you (should?) usually write out the allophone if you are using slashes for a broad phonemic transcription the way you would when using square brackets for a (comparatively) narrow phonetic transcription.
–
tchristJul 7 '12 at 20:09

In American English, either is acceptable. "Dah-tuh" is more common than "day-tuh" in my personal experience, though it's hard to say which is more prominent overall. (Regional speech differences can inflect the decision about pronunciation as well.)

My personal experience is the opposite -- but that's just me :) The only time I ever hear dah-tuh is on television.
–
Billy ONealJan 26 '11 at 22:26

2

This is amusing, since for almost every other English word, Americans use a (very) long "a" vowel sound, whereas Brits use a short one. I suppose the case is reversed here.
–
NoldorinJan 26 '11 at 23:50

I vaguely remember being told that day-ta was the correct pronunciation, and that was because there was a vowel (the second 'a') following the consonant (the 't'). Now whether or not that actually applies, someone please comment because I'd love to know if I was given a load of hogwash there.

Personal experience, I find that I hear and use day-ta more than dah-ta. It is similar to the different ways that 'SQL' is pronounced among us techies - some spell it out, and some pronounce it as "sequel". Thinking about it, I find that when it is the word "data" all by itself, I use day-ta, but when it is part of another word ("database", for example) I tend to use dah-ta instead. Again, not sure if this is something that I just happened to have picked up over the years or if it is even correct. Anyone else notice the different pronunciation in situations like this?

The NOAD uses "d" for "flap t" in its pronunciation symbols. I don't know of any good justification for this; /d/ and /t/ are perceived as different phonemes in American English, even in cases where they are both replaced by a flap.
–
Peter Shor Jul 7 '12 at 13:02